"I'm servicing my rear derailleur (Shimano RX100 7 speed.) The two pulleys are slightly different (one is ""beefier"" and has a metal sleeve fused inside it.) Which goes on top?
Thanks."
Shimano Pulleys Question
Fri, 03/26/2004 - 8:30am
Fri, 03/26/2004 - 9:21am
#1
"to avoid a case of the ""squeeks""..."
"..be sure to remove, clean and add a dab/light coat of grease inside the metal sleeve (bushings) and the inner plastic rollers.
As for the original question, go with what Fred wrote. Honestly though, I've often wondered myself when servicing and haven't really noticed a difference myself. Maybe I've been lucky putting them back in their proper orientation, if there is one..
FWIW,
http://www.shimano-europe.com
is a good reference for exploding PDF diagrams of Shimano equipment."
Fri, 03/26/2004 - 9:33am
#2
a dab? all these years, I've been packing the things FULL of Phil Wood... (& have apparently been running them upside down too.)
Fri, 03/26/2004 - 9:41am
#3
a dab-a-do
No harm in FULL - other than there's more muck to wipe off the pulleys after oiling your chain each time.
Fri, 03/26/2004 - 10:14am
#4
The top pulley is known as the jockey pulley; the bottom, the tension pulley.
The jockey should have a tiny bit of float. Shimano calls this feature Centeron (as it centers on - actually, under - the cog). That name used to be stamped on the side of the jockey, maybe no longer. But that's the best way to tell, it oughta have some side-to-side play after tightening it down.
Fri, 03/26/2004 - 12:02pm
#5
"Yup, one pulley is marked ""centeron"" (of course, it's the one I've had on bottom for a few years.)
:(
These are a bit worn. I'm planning on ordering replacements during the great Performance club deal thingie...
"
Fri, 03/26/2004 - 12:59pm
#6
centeron
Shimano sez the pulley float is necessary for proper indexing, that it allows the chain to self-center under the cog if the derailer adjustment isn't perfect. Whether it actually matters or not is anyone's guess.
Fri, 03/26/2004 - 1:22pm
#7
centeron...
... actually precedes indexing. It was developed as an aid to friction shifting, a sort of self-correcting mechanism, to reduce the need for 'trimming'.
It's really not necessary for indexing, but could help if the derailleur is slightly misadjusted.
Fri, 03/26/2004 - 8:38am
#8
on top
Based on my 9-Speed Deore XT dereilleur, the beefy pulley goes on top.
Fri, 03/26/2004 - 6:16pm
#9
"The XTR on my touring bike has a brass bushing in the lower pulley and a ceramic bushing and sleeve in the upper pulley. When properly tighted in the derailleur cage, the pulley that is the upper should have the previously mentioned ""float"", i.e. lateral movement.
IMHO, these are both poor quality products as my experience is that the brass brush will corrode much more rapidly than an equivalent Campagnolo and the ceramic bushings will crack after some use. If there is a choice, maybe replacement with one of the aftermarket units is the best plan."
